ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM TROPICAL STORM MITCH DISCUSSION NUMBER 8 NATIONAL WEATHER SERVICE MIAMI FL 5 PM EDT FRI OCT 23 1998 SATELLITE IMAGES INDICATE THAT THE CLOUD PATTERN ASSOCIATED WITH MITCH HAS NOT CHANGED SIGNIFICANTLY DURING THE DAY. IT CONTINUES TO HAVE WELL DEFINED CLOUD BANDS WRAPPING AROUND THE SYSTEM BUT LACKS OF DEEP CONVECTION AND CENTRAL FEATURES. RECON JUST MEASURED A MINIMUM PRESSURE OF 997 MB NAD 50 KNOT WINDS. THE WESTERLY WINDS ASSOCIATED WITH AN UPPER-LOW WHICH FORMED JUST WEST OF THE TROPICAL CYCLONE IS DISRUPTING THE OUTFLOW AND AS LONG THIS FEATURE IS PRESENT STRENGTHENING IS NOT LIKELY. UNANIMOUSLY...ALL MODELS WEAKEN THE UPPER-LOW AND DEVELOP A SIGNIFICANT 200 MB ANTICYCLONE OVER MITCH. HOWEVER...THERE ARE NO INDICATIONS OF WESTERLIES RELAXING AT THIS TIME. IF THE UPPER-LEVEL ANTICYCLONE FORMS...IT WOULD BE AN IDEAL ENVIRONMENT FOR STRENGTHENING AND IN FACT...BOTH SHIPS AND THE GFDL MODELS BRING MITCH TO HURRICANE STATUS. KNOWING THAT THE GLOBAL MODELS TEND TO GET RID OF UPPER-LEVEL WESTERLIES TOO FAST...THE OFFICIAL FORECAST CALLS FOR NO SIGNIFICANT CHANGE IN INTENSITY DURING THE NEXT 24 HOURS AND IF MITCH SURVIVES...THEN STRENGTHENING SHOULD BEGIN. MITCH HAS BEEN NEARLY STATIONARY OR JUST A NORTH-NORTHWEST DRIFT. A MID-LEVEL TROUGH LOCATED ALONG THE EAST COAST OF THE UNITED STATES IS FORECAST TO MOVE OUT OF THE AREA AND BE REPLACED BY A RIDGE. CONSEQUENTLY...A SLOW NORTH-NORTHWEST AND THEN NORTHWEST TRACK SHOULD BEGIN IN ABOUT 24 HOURS. THIS IS CONSISTENT WITH MOST OF THE MODELS WHICH ARE FORECASTING MITCH TO STAY OVER THE NORTHWESTERN CARIBBEAN FOR THE NEXT 3 TO 5 DAYS. NO WATCHES OR WARNINGS ARE NECESSARY AT THIS TIME BUT INTERESTS IN THE WESTERN CARIBBEAN SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM. AVILA FORECAST POSITIONS AND MAX WINDS INITIAL 23/2100Z 13.0N 78.1W 50 KTS 12HR VT 24/0600Z 13.1N 78.2W 50 KTS 24HR VT 24/1800Z 14.0N 78.5W 60 KTS 36HR VT 25/0600Z 14.7N 78.7W 70 KTS 48HR VT 25/1800Z 15.5N 79.5W 80 KTS 72HR VT 26/1800Z 17.0N 81.5W 80 KTS NNNN